Furnace-regulator system



Mar. 27, 1923.

. 1,449,881. 0. A. BODDIE.

FURNACE REGULATOR SYSTEM.

FILED JUNE 25, 1919. 2 SHEETS-SHEET l- WITNESSES- INVENTOR W x066 /I. 804096,

Mari' 27, 1923.

' 1,449,881; 'C. A. BODDIE.

FURNACE REGULATOR SYSTEM.

FILED JUNE 25, 1919- 2 SHEETS SHEE T 2- I WITNESSES:

[NVENTOR Patented Mar. 27, 1923.

CLARENCE A.

BODDIE, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR 'I'O WESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENN- SYLVANIA.

FURNACE-REGULATOR SYSTEM.

Application filed June 25, 1919. Serial No. 306,725.

To all whom it may concern 1 Be it known that I, CLA'nENon A. Boumn, a citizen of the United States and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania; have invented a new and useful Improvement 1n Furnace-Regulator Systems, of which the V movable electrode type, 7 25.

' a furnace-regulator to be effected by following is a specification.

My invention relates to regulator systems and particularly to regulator systems for governing the operation of the movable electrodes in electric furnaces.

One object ofmy invention is to provide system that shall govern the operation of the movable electrodes to maintain equal heating effects by the various electrode arcs; that shall prevent movement of the electrodes in case of failure of the main supply-circuit connected to the furnace, and that shall prevent any hunting action or lowering of any electrode into the bath of material being treated.

In operating an electric. furnace of the it"is desirable to lower each electrode automatically raise and furnace condition in accordance with some and to maintain a constant electrode arc..

In order to effect such regulation, it is customary to control each electrode in accord-- ance with the current flowing through it without regard to the amount of power taken by the electrode. However, it is apparent that such regulation is impractical in many cases, inasmuch as no compensation is made for variations in power factor and the consequent wattless current and no account is taken ofthe variationsin resistance of the different portions of the charge which is encountered by the electrodes. Consequently, 'n current-regulated heating effects are liable the electrode arcs, with the accompanying lowering of the quality of the material produced by the furnace and the more rapid deterioration of the furnace by reason of the variations in temfurnaces, unequal perature to which it is subjected.-

In the furnace-regulator system comprising my invention, each electrode s raised and lowered by means of an electric motor and each motor is controlled not only in accordance with the current flowing through the associated electrode but also in accordance with the potential obtaining across the arc produced by the electrode. Consespectively operated in accordance with the v current flowing through the electrode and in accordance with the potential across the arc producedby the electrode, means for insertmg a resistor in shunt to one of said electromagnets, when the motor is energized,

in order to prevent hunting action by the regulator, and means in case of failure of the main supply circuit, for returning the regulator to neutral position to prevent further operation of the electrode motor.

Moreover, the connection of one of the main control magnets of each regulator across the associated electrode arc insures the electrodes against any movement into the bath of material being treated. lhus, in case any electrode encounters a portion of the charge which has a very high resistance, the current electromagnetof the regulator will attempt to lower the electrode even into the bath of material being treated and the potential electromagnet of the regulator will oppose such operation and, when the electrode engages the surface of the bath of material, the potential electromagnet is short-circuited to prevent further lowering of the electrode.

In practicing my invention, it is possible to vary the energization of the potential electromagnet to prevent any hunting action whether the electrode is being raised or lowered in place of varying the energization of both the current and the potential electromagnet to prevent any hunting action.. I

The regulator ject matter of closely related to that disclosed in applicants copending applications, Serial Nos. 306,723 and 306,72 l, filed June 25, 1919, and assigned to the Westinghouse Electric & Manufacturing Company.

In the accompanying drawing, Figure l'is a diagrammatic view of a furnace-regulator system embodying my invention,,and Fig. 2 is a diagrammatic View of a furnaceregulator system embodying a modification of my invention.

the present application is flowing through the electrode and in accordance with the potential across the electrode arc to maintain a substantially-constant arc.

Inasmuch as these regulators operate in the same manner and are of like construction, it is deemed unnecessary to illustrate and describe more than one of them. Accordingly, only the regulator associated with the electrode 6, is illustrated in the drawing and will be described in detail.

A motor 10, comprising an armature 11 and a field winding 12, which is directly connected across supply-circuit conductors 13' and 14, is provided for raising and lowering the electrode 6. The motor 10 is mechanically connected to the electrode 6 in any suitable manner, as by means of a shaft 15, a

winding drum 16, and a flexible connector 17, which passes over a pulley 18.

A regulator 19 which controls the operation of the motor 10, comprises two main control electromagncts 20 and 21, which are respectively operated in accordance with the current flowing through the electrode 6 and ,is provided with a dashpot 28 in accordance with the potential across the are produced by the electrode. and two switches 22 and 23, which respectively serve to connect the motor across the supply conductors 13 and 14 in order to operate it in a clockwise and in acounterclockwise direction.- The main control electromagnet 20 comprises a winding 24, which is connected to the three-phase supply conductor 9 by means of a current transformer 25, and a core armature 26. The core armature 26 is pivotally connected to a contact arm 27 and for governing its speed of operation.

The main control electromagnet 21 comprises a winding 28, which is connected between the electrode 6 and the bath of material 3. and core armature 29. The core armature 29 is pivotally connected to the contact arm 27 and is provided with a dashpot 30 for governing the speed of its operation. The contact arm 27 is pivotallymounted at a point- 31 intermediate. the points of connection to the core armatures 26 and 29. Two main contact members 32 and 33 are mounted upon the contact arm 27 intermediate the fulcrum point 31- and the point of connection of the core armature 29 to the'contact arm and are adapted to engage contact members 34 and 35 according to the position of contact arm 27. Springs members 32 and 33 disengaged from the contact members 34 and 35 when the electromagnets 20 and 21 are de-energized. The

contact members 32 and 33 are connected to the supply conductors 13 and 14 through a resistor 37.

The switch 22 comprises a winding 38, which is connected across the supply'conductors 13 and 14 upon engagement of the contact members 32 and 34, and a core armature 39 which operates two switch members 40 and 41 and two interlock switch members 42 and 43. The switch members 40 and 41, upon operation of the switch 22, connect the armature 11 across the supply conductors 13 and 14 for rotating the motor 10 in a clockwise direction to lower the electrode 6 in the furnace 1. The interlock switch member 42 connects a resistor 44 in shunt to the winding 28 of the main electromagnet 21 upon operation of the switch 22 in order to change the setting of the regulator and prevent hunting action.

The switch 23 comprises a winding 45, which is connected across the supply conductors 13 and 14 upon engagement of the contact members 33 and 35, and a core armatlire 46 which operates twoswitch members 47 and 48 and two interlock switch members 49 and 50. Upon operation of the switch 23, the two switch members 47 and 48 connect the armature 11 across the supply conductors 13 and 14 for operating the motor 10 in a counterclockwise direction to raise the electrode 6 from the bath of material 3.

The interlock switch member 49 serves to connect the resistor 51 in shunt to the wind- 1 prevent any hunting action when the motor\ 1s being operated in a counterclockwise direction, and the interlock switch member 42 connects the resistor 44 in shunt to the winding 28 in order to prevent any hunting action when the motor is being operated in a clockwise direction.

The two interlock switch members 43 and 50 connect a brake electromagnet 52 across the supply conductors 13 and 14 when the two switches 22' and 23 are simultaneously released. The relay 52 completes a dynamic braking circuit through a resistor 53 for the motor 10. Thus, when the motor 10 is operating in a clockwise or in a counterclockwise direction. the release of the switch 22 or the switch 23 immediately energizes the brake relay 52 for completing a dynamic brake to effect a quick stopping of the motor. Condensers 54 and 55 and resistors 56 and 57 are connectedin shunt to the windings 45 and 38 of the switches 23 and 22 in order to improve the operation of the main contact members 33 and 35 and, 32 and 34.

In case the currentflow throughthe electrode 6 is raised above a normal amount and the potential across the are formed bythe electrode is below normal value, the energization of the electromagnet 2O isin'creased and the energization of the electromagnet 21 is decreased to effect engagement between the contact members 33 and 35. Upon engagement of the contact members 33 and 35, a circuit is completed for operating the switch 23, which extends from the supply circuit 14, through a portion of the resistor 37, contact arm 27, main contact members i 33 and 35, and the coil 45 of the switch 23, to the supply conductor 13. The switch members 47 and 48 complete a circuit through the armaturp 11 for rotating the motor in a Accordingly, electrode 6 is raised from the bath of material 3 to effect a reduction in the current flow through the electrode and an increase in the potential across the arc formed by the electrode. 4 If the main control electromagnets 20 and 21 were controlled solely in accordance with the current flowing through the electrode, and in accordance with. the potential across the are formed by the electrode, then the contact arm 27 would not be operated to separate the contact members 33 and 35 and to de-energize the motor 10 for preventing further raising of the electrode 6 until normal circuit conditions obtained in the circuit of the electrode 9. Consequently, the motor 10 and the various moving parts of the regulator would overtravel and over-compensate the furnace so that the electrode 6 would be raised above the desired point. The current flow through the electrode would be reduced below a normal amount, and the potential across the electrode arc would' be increased above normal value. Such overtravel of the moving parts of the regulatorwould cause the so-calle and undesirable hunting action.

In order to prevent such overtravel and hunting action when the motor is being operated in a counterclockwise direction to reduce the current flow through the electrode,

the interlock switch member 49 connects the resistor 51 in shunt to the winding 24- of the main control electromagnet 20. The shunt circuit across the winding 24 changes the setting of the regulator and effects the separation of the contact members 33 and 35 to deenergize the motor 10 just. prior to the obtaining of normal current flow through the electrode and normal potential across the are formed by the electrode.

Assuming the current flow through the creased to effect engagement between the contact members 32 and 34. Upon engagement between the contact members 32 and 34, the" switch 22 is operated by a circult ,which extends from the supply conductor 14, through a portion of the resistor 37, contact arm 27 ,main contact members 32 and 34, and the winding 38 of the switch 22, to the supply conductor 13. Thereupon, the switch members 40 and 41 are. operated to complete a circuit through the armature 11 and effect rotation of the motor '10 in. a clockwise direction. The clockwise rotation of the motor 1 lowers the electrode 6 to increase the current flow through it and reduce the potential across the arcformed by it.

Simultaneously with the operation of the motor 10 by the switch 22, the interlock switch member 42 connects the resistor 44 across the winding 28 of the electromagnet 21 for changing the setting of the regulator in order to prevent a hunting action. Upon shunting of the winding 28, the setting of the regulator '19 is changed so that the contactmembers 32 and 34 are separated to deenergize.the motor 10 just prior to the obtaining of normal electrode-circuit conditions. 1

Inasmuch as the electrode 6 is jointly controlled by the electromagnets 20 and 21, in accordance with the currentflow through theelectrodeend in accordance with the potential across the electrode arc, the heating effect of the electrode is maintained substantially constant. Moreover, in case the electrode should, from any cause whatever, be lowered into engagement with the surface of the bath of material 3, the winding 28 of the electromagnet 21 wouldbe short-circuited to immediately effect the separation of the contact members 32 and 34 and thus prevent the lowering of the electrode into the bath of material 3. The variation of the energization of the electromagnet 20' by the shuntingresistor 51, when the motor is operating in a counterclockwise direction, and

has been deemed sufficient to describe such means alone in the system disclosed in Fig. 2.

' 42, which is controlled by the switch 22, connects a resistor 44 in shunt to the winding 28 of the electromagnet 21, as in the system disclosed in Fig. l of the drawing.

Assuming the current flow through the electrode 6 to be above a normal amount and the potential across the electrode arc to be below normal value, and the contact members 33 and 35 to be moved into engagement with each other by the electromagnets 20 and 21, the switch 23 will be operated to effect counterclockwise rotation of the motor 10. Such rotation of the 'motor, as in the system shown in Fig. 1, raises the electrode 6 to decrease the current flow through it.

Simultaneously with the energization of the motor 10, the interlock switch member 49 short-circuits the resistor 60 which is normally included in series with the winding 28. Accordingly, the energization of the electromagnet 21 is increased to change the setting of the regulator and effect disengagement of the contact members 33 and 35 just prior to the obtaining of normal current flow through the electrode 6 and normal voltage across the electrode arc. Thus, hunting action is prevented when the motor is operating in a counterclockwise direct-ion by increasing the energization of the main control electromagnet 21.

I11 case the regulator is operated by a decreased current flow through the electrode 6 to effect engagement between contact members 32 and-34, the switch 22 and the motor 10 are operated to lower the electrode 6 into the furnace. Simultaneously with the energization of the motor 10, the interlock switch member 42 connects the resistor 44 in shunt to the winding-.28 of the electromagnet 21. The energization of the electromagnet 21 is decreased to change the setting of the regulator and thus to effect separation of the contactmembers 32 and 34 just prior to the obtaining of normal circuit conditions in the circuit of the electrode 6.

Thus, when the motor is operating in a counterclockwise direction, the energization of the main control-magnet 21 is increased by short-circuiting the resistor 60 to prevent hunting action and, when the motor is operating in a clockwise direction, the energization of the electromagnet 21 is decreased by connecting the resistor 44 across the winding 28 to prevent hunting action.

Modifications in the system and arrangement and location of'p'arts maybe made within the spirit and scope of my invention,

and such modifications are intended to be able electrode, 'a regulator for governing the operation of said electrode and comprising two electromagnets operated in accordance with the electrical conditions of the electrode circuit, and means comprising a resistor for varying the energization of each electromagnet to prevent hunting action by the regulator.

2. In a furnace-regulator system, the combination with a movable electrode and a motor for operating said electrode, of a regulator for governing the motor to maintain a substantially constant arc, said regulator comprising an electromagnet energized in accordance with the current flowing through the electrode and a second electromagnet energized in accordance with the potential across the electrode arc, and means for deenergizing the winding of each of f said electromagnets, under certain operating conditions, to prevent hunting action by the regulator.

3. In a furnace-regulator system, the combination comprising a movable electrode, a motor for raising and lowering said electrode. a regulator for controlling said motor to maintain a. constant electrode arc and comprising a. plurality of electromagnets operated in accordance with the electrical conditions of the electrode circuit, a plurality of resistors, and means for shunting said electromagnets by said resistors, under predetermined conditions, to prevent hunting act-ion by the regulator.

4. In a furnace-regulator system, the combination comprising a movable electrode, a motor for raising and lowering said electrode, a regulator for controlling the operation of the motor and comprising an electromagnet energized in accordance with the turrent flowing through the electrode and a second electromagnet energized in accordance with the potential across the are produced by the electrode, means comprising a resistor for shunting said current electromagnet to prevent hunting action when the electrode is being raised, and means comprising a resistor for shunting said potential electromagnet to prevent hunting action when the electrode is being lowered.

5. In a furnacerregulator system, a movable electrode, a motor for raising and lowering said electrode. a regulator comprising an electromagnet energized in accordance with the potential across the electrodearc and adapted to maintain a substantiallyconstant electrode arc, and means for inserting resistance in shunt to said electromagnet for preventing hunting action.

6. In a furnace-regulator system, a movable electrode, a motor for raising and lowering said electrode, a regulator comprising an electromagnet energized in accordance with the potential across the electrode arc and adapted to control said motor and maintain a substantially-constant electrode are, said electromagnet being connected to effect de-energization of said motor in case the electrode is lowered into contact with the surface of the'material being treated, and means for inserting resistance in shunt to said electromagnet for preventing hunting action by the regulator.

7. In a furnace-regulator system, the combination comprising a movable electrode, a supply circuit connected to the electrode, a motor for raising and lowering said electrode, a regulator for controlling said motor to maintain a constant electrode arc, said regulator comprising two electromagnets operated in accordance with the electrical conditions of the electrode circuit, and means comprising resistors connected in shunt to said electromagnets for preventing hunting action by the regulator, said regulator having means for returning it to a neutral position in case of failure of the supply, circuit.

8. In a furnace-regulator system, the combination comprising a supply circuit, a movable electrode connected to the supply circuit, a regulator for controlling the movement of said elect-rode formaintaining a constant are, said regulator comprising an electromagnet-operated in accordance with the current flowing through the electrode and an electromagnet operated in accordance with the potential across the electrode arc, and means for inserting resistance in circuit with said electromagnets to. prevent hunting action, said regulator having means for returning it to a neutral position in case of failure of the supply circuit. I

9. In a furnace-regulator system, a movable electrode, means for raising and lowering said electrode, a regulator comprising an electromagnet energized in accordance with the potential across the are produced by the electrode for controlling said means to maintain a substantially constant arc, and means for varying the circuit of said electromagnet to prevent hunting action by. the regulator.

10. In a furnace-regulator system, the combination with a movable electrode, and means for raising and lowering said electrode,-of a regulator for controlling said means to maintain a constant electrode arc and comprising an electromagnet energized in accordance with the potential across the arc, and means for varying the energization of said electromagnet to prevent hunting action by the regulator. 11. In a regulator system, the combinatlon with a supply circuit, a plurality of movable electrodes connected to the supply I circuit, and a motor for operating each of said electrodes, of a regulator connected to each motor and the associated electrode for maintaining a substantially constant electrode arc, each of said regulators comprising two eleotromagnets energized in accordance with the circuit conditions of the associated elect-rode, a plurality of resistors, and means for inserting said resistors in shunt to the electromagnets for preventing hunting act-ion, said regulators comprising means for preventing the lowering of any of the electrodes into the bath of material being treated.

12. In a regulatorsystem, a supply circuit, a resistance-varying means in said circuit, a regulator comprising two electromagnets for governing the operation of said means when operated in accordance with the electrical conditions of the supply circuit, and means comprising a resistor for partially deenergizing each electromagnet to prevent hunting action by the regulator.

13. In a regulator system, the combination with a supply circuit and a resistancevarying means in said circuit, of a regulator for governing the operation of said means to maintain substantially-constant supply-circuit conditions, said regulator comprising an electromagnet energized in accordance with the current flowing through the electrode and a second electromagnet energized in accordance with the potential across the resistance-varying means, and means for partially deenergizing the winding of each of said electromagnets, under certain operating conditions, to prevent hunting action by the regulator.

14:. In a furnace-regulator system, a movable electrode, a motor for raising and low ering said electrode, and a regulator having a current and a potential electromagnet for operating said motor to maintain the are produced by said electrode substantially constant, said regulator being adjusted to prevent operation of the motor in case of failure of the electrode circuit.

15. In a furnace-regulator system, a plurality of movable electrodes, a motor for raising and lowering each of said electrodes, a regulator for governing each of said motors to maintain the electrode arcs substantially; constant, and means for adjusting each of said regulators for return to a neutral position in case .of failure of the electrode circuit.

16. In a furnace-regulator system, a movable electrode, a motor for raising and lowering said electrode, a regulator for operating said motor to maintain a constant arc and having an electromagnet operated in accordance" with the current flowing through the electrode and a second electromagnet operated in accordance with the potential across the are producedby the electrode,

tral position in case of failure of the elec-- trode circuit. 7

18. In a furnace-regulator system, the combination with a movable electrode, and a motor for raising and lowering the electrode, of a regulator having a current electromagnet and a potential electromagnet operated in accordance with the condition of the electrode circuit for operating said motor to maintain a substantially-constant electrode arc, said potential electromagnet being de-energized in case the electrode is lowered into engagement with the material being treated, and means for adjusting the regulator for return to a neutral position in case of de-energization of the electromagnet by engagement of the electrode with the material being treated.

19. In a furnace-regulator system, the combination with a movable electrode, and a motor for raising and lowering said electrode, of a regulator having two electromagnets energized in accordance with the electrode-circuit conditions for operating said motor to maintain a substantially constant electrode arc, means associated with one of said electromagnets for preventing hunting action when the electrode is being .lowered, and means associated with the second electromagnetfor preventing hunting actionwhen the electrode is being raised.

20. In a furnace-regulator system, the combination with a movable electrode, and a motor for raising and lowering the electrode, of a regulator for controlling said motor and comprising an electromagnet energized in accordance with the current flowing through the electrode and a. second electromagnet energized in accordance withthe potential across the are produced by the electrode, means connected with. said current electromagnet for preventing hunting action when the electrode is being raised, and means connected to the potential electromagnet for preventing hunting action when the electrode is being lowered.

2-1. In a furnace-regulator system, a movable electrode, a motor for raising and lowering said electrode, a regulator having two electromagnets operated in accordance with electrode-circuit conditions for operating said motor to maintain a substantially constant electrode arc, means for adjusting said regulator to prevent operation of the motor in case of failure of the electrode circuit,

and means for changing the setting of said magnets to prevent hunting action by said regulator.

22. In a furnace-regulator system, the combination with a supply circuit, a pluralityof movable electrodes connected to the supply circuit, and a motor for operating each of said electrodes, of a regulator connected to each motor and the associated electrode for maintaining a substantially-constant electrode arc, each of said regulators having an electromagnet energized in accordance with the current flowing through the associated electrode and a second electro-magnet energized in accordance with the potential across the are produced by the associated electrode, and means associated with said regulators for preventing the low- I 24. In a furnace regulator system, a movable electrode, a regulator for governing the operation of said electrode and comprising two electromagnets operated in accordance with the electric conditions of the electrode circuit, and means for varying the energization of said electro-magnets to preventhunting action by the regulator.

25. In a regulator system, a supply circuit, a resistance-varying member in said circuit, a motor for operating said member, a regulator comprising a current electromagnet and a potential electromagnet for governing said motor to maintain constant supplycircuit conditions and means for adjusting said regulator to return it to neutral position in case of failure of voltage on the supply circuitQ In testimony whereof, I have here-unto subscribed my name this 20th day of June,

CLARENCE A. BODDIE. 

